The most common type of flagpole installation is the in-ground foundation sleeve method. This calls for 1' of the flagpole to be encased in the ground sleeve for each 10' of exposed flagpole height.

The diameter for the sleeve should be at least 2" greater than the outside diameter of the flagpole containing the area between the flagpole and the sleeve that is filled with dry sand.
These Ground Sleeves are supplied with a base plate and grounding spike.